While that stance brought scorn from environmentalists and countries that favor stronger action to fight global warming, there are signs that the administration is finding a receptive audience among other major fossil-fuel producers, including Russia, Saudi Arabia and Australia.

President Trump’s international energy and climate adviser, Wells Griffith, hosted a panel discussion on fossil fuels at the United Nations conference, arguing that the developing world would be heavily reliant on coal, oil and gas for some time and that it was in the world’s interest to find more efficient ways of developing and burning those fuels.

Midway through, the panel was interrupted by scores of noisy protesters, who chanted, “Shame on you!” and “Keep it in the ground!”

“The United States has an abundance of natural resources and is not going to keep them in the ground,” Mr. Griffith said. “We strongly believe that no country should have to sacrifice their economic prosperity or energy security in pursuit of environmental sustainability.”

With its stance, the United States was emerging as the leader of an informal movement to promote coal and other fossil fuels — despite reports, including by the government’s own scientists, that the planet is growing dangerously warmer because of greenhouse gasses.

Mr. Griffith’s position was shared by Patrick Suckling, Australia’s ambassador for the environment, who was also on the panel and who agreed that “fossil fuels are projected to be a major source of energy for a significant time to come.” He spoke in favor of technology for capturing carbon dioxide from coal plants and burying it, and noted that such technology could be exported.

The public endorsement of fossil fuels came two days after the Trump administration helped to block the United Nations climate conference from embracing the findings of a major scientific report on global warming. It amounted to what might be the most dramatic show of disdain for the Paris Agreement on reducing greenhouse emissions — at a gathering meant to establish a set of rules for implementing the deal — since President Trump announced that the country would abandon the pact.

The United States — along with Saudi Arabia, Kuwait and Russia — refused to allow a collective statement that would “welcome” the report, issued by the Intergovernmental Panel on Climate Change, which detailed a variety of strategies for cutting global fossil-fuel emissions roughly in half by 2030 in order to avoid many dangerous climate impacts.

Instead, the countries, all major oil and gas exporters, demanded the conference only “note” the existence of the report and thank the scientists for their work.

While the difference between welcoming and noting a report might seem slight, in the world of diplomacy it essentially means the difference between endorsement and neutrality. The 2015 Paris Agreement almost fell apart in a feud over the words “should” versus “shall.”

At the same time, American career diplomats are working, behind the scenes, to help negotiate with other countries over details for a “rule book” that will allow the Paris agreement to become operational.

In seeking to water down the language adopting the United Nations report, delegates said, the Trump administration sent a powerful message that it not only rejects the Paris Agreement but also the scientific underpinning of the international climate change negotiations itself.

“I don’t see any reason why any government or country can deny what the science says,” said Amjad Abdulla of the Maldives, the chief negotiator for a bloc of island nations known as the Alliance of Small Island States. “It sends a very bad signal.”

Image

Wells Griffith, President Trump’s international energy and climate adviser, on Monday. CreditKarolina Jonderko for The New York Times

The United Nations report forecast what would happen if average global temperatures rose by 1.5 degrees Celsius, or 2.7 degrees Fahrenheit, over preindustrial levels and warned “there is no documented historic precedent” for the scale of changes needed to avoid the worst damage.

Ever since President Trump announced last year he would pull the United States out of the Paris agreement, observers have been watching for signs that America’s disavowal of the pact could encourage other countries to slacken their own efforts at cutting emissions.

“It’s hard to draw a direct cause and effect, but we know that investors do pay close attention to political signals,” said Joseph Curtin, a senior fellow at the institute and the author of its report. “The Paris Agreement sent a strong signal that carbon-intensive investments were risky. Now we’re seeing signals the other way.”

The United States’ alignment with Kuwait, Russia and particularly Saudi Arabia also injected a new dynamic that several diplomats said they found worrisome. Saudi Arabia in particular has long been accused of outright obstruction in the climate talks. Several diplomats said seeing America standing with Saudi Arabia in rejecting science was shocking.

“The U.S. along with Saudi Arabia are playing a clear and calculated spoiling role in the climate change negotiations,” said Ian Fry, the lead negotiator for Tuvalu. He called the countries’ official indifference to the United Nations report “truly disturbing.”

Others noted that the United States and Saudi Arabia remained at odds on a number of issues, like whether developed and developing countries should be held to the same transparency standards for meeting emissions-cutting goals, and dismissed the idea that the countries were working together in a coordinated way to derail the negotiations.

George David Banks, a former White House energy adviser in the Trump administration, said the shared position of the United States and Saudi Arabia on the United Nations report merely reflected their mutual energy interests and concerns about a growing international movement around divestment and the rejection of fossil fuels in response to climate change.

“The United States and Saudi Arabia both have abundant resources of fossil energy,” Mr. Banks said. “When you have a Republican administration that supports energy dominance as a foreign policy goal, it makes sense for the United States to take the position that happens to align with the Saudis.”

Image

Protesters interrupted the United States presentation in Katowice on Monday. CreditKarolina Jonderko for The New York Times

The disagreement over the United Nations report may have helped to fundamentally alter the perception of what role the United States intends to play in the negotiations from now on under the Trump administration.

Climate diplomats have generally operated over the past year with the understanding that, while President Trump has vowed to withdraw the United States from the Paris Agreement and takes every opportunity to publicly denounce the accord, the administration was not actively seeking to undermine it or persuade other countries to also reject it.

Yet at the Group of 20 talks in Buenos Aires this year, where the United States was the lone holdout on a statement reiterating nations’ support for the Paris Agreement, a senior White House official made a point of noting that Turkey, Saudi Arabia and Russia also expressed doubts about staying in the accord. “You’re seeing a little bit of the coalition fraying,” the administration official said in a background briefing.

In the meantime, State Department negotiators have continued to press countries like China and India on issues like adopting stricter transparency measures — a delicate task, some analysts say, given the Trump administration’s public stance on the agreement.

“I think the U.S. doesn’t have a huge amount of direct influence right now because of President Trump’s position,” said Nigel Purvis, a top environmental negotiator under Presidents Bill Clinton and George W. Bush and the chief executive of Climate Advisers, a consulting firm.

“But the U.S. negotiators are highly respected and experienced, and people understand that the perspectives they have on requiring more transparency from China, India and others are the same perspectives that any future administration would likely have,” he added. “So countries are still taking them seriously.”